1. Field of the Invention
The current invention directed to an improved fuel injection device for an internal combustion engine.
2. Description of the Prior Art
A fuel injection device known from DE 28 08 731 C2 includes a fuel injection valve, which has an injection valve member that is guided so that it can slide in a bore of a valve body and control at least one injection opening. The pressure prevailing in a pressure chamber of the fuel injection valve can move the injection valve member in an opening direction, counter to the force of a closing spring disposed in a spring chamber, in order to unblock the at least one injection opening. A predetermined pressure is maintained in the spring chamber and this spring chamber can, for example, be connected to a low-pressure region. In order to initiate fuel injection, highly pressurized fuel is supplied to the pressure chamber of a fuel injection valve from a high pressure source. An electrically controlled valve at least indirectly controls a connection from the pressure chamber or the high pressure source to a relief chamber. In order to terminate the fuel injection, the valve opens the connection to the relief chamber so that the pressure in the pressure chamber decreases and the fuel injection valve closes. The pressure in the pressure chamber decreases very sharply so that in some circumstances, it falls below the vapor pressure of the fuel so that cavitation occurs. This creates intense wear and loud noise, which are to be avoided.
The fuel injection device according to the invention has the advantage over the prior art that a check valve permits a pressure compensation between the pressure chamber and the spring chamber when the pressure in the pressure chamber is lower than in the spring chamber. This prevents the pressure in the pressure chamber from dropping below the vapor pressure of the fuel so that no cavitation occurs. The wear and noise emission of the fuel injection device according to the invention are therefore reduced.